View Single Post
smurfbus smurfbus is offline
smurfbus's Avatar
Join Date: Aug 2009
Location: Europe
Posts: 1,481
My new alternator has bigger axle so the concave spacer wont fit?

Edit. Skip to the second post!

EDIT: It's an AL400X, it reads on the side. It seems the diode packs are soldered on the wiring on the plus side.
EDIT2: I just bought a new Valeo Paris Rhone from Germany and will see how much it takes to rebuild this al400x for spare.

Its on my 79 930 so it has been converted to internal voltage regulator model. I have very low voltage like 1.6V at the blue wire at the tachometer and red/black has about one volt lower than battery voltage? IIRC the alternator worked just fine before the wiring melt down 2010. I need to check the starter posts but I have full voltage at the red wire on the alternator.

The red light is on all the time when ignition is on. What gives up on the alternator, the diodes?

Blue wire was on D+
earth on D- and on the block bolt
red ones on B+

The voltage regulator looks like this one except the positive connector is different on mine.

These are the troubleshooting steps I will test next trying to figure out the problem:
To trouble-shoot the problem, you need to check the various sections independently. Thus the first check: Connect +12 volts from the battery to the DF terminal on the relay board. This is the maximum field current situation, and should result in maximum output of the alternator. Note that this checks the B+ diodes, the alternator windings, and the common diodes. It does NOT check the D+ diodes.

To check the D+ portion of the system, it is necessary to find out if the D+ output can produce enough current to drive the alternator to full output. To do this, short the D+ and DF terminals on the relay board. This will provide the maximum field current to the alternator that the alternator ITSELF can supply (not the battery, as in the earlier check) and so checks the remainder of the circuitry. If this test puts the light out, then the alternator is good, and the trouble is elsewhere. If it doesn't, then the alternator is almost certainly bad, with one other possibility:

In the Bosch system, the size of the charge warning lamp bulb is critical. Too low a wattage bulb will not supply enough field current for "bootstrap" operation to be reliable. The Bosch book that I have states that the lamps must be at least 2 watts for 12 volt systems. If you have replaced your charge warning lamp recently, then too small a lamp may be your culprit.
************************************************** *******************************
79 930: HX40S#16, MS3pro+ID1000+044+E85, Ignition: 123/TUNE/MSD6A, True split BB, 2*turbosmart38

Last edited by smurfbus; 05-24-2013 at 11:12 AM..
Old 05-06-2013, 09:23 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)